Isoprenoids constitute an extremely large and diverse group of natural products that have a common biosynthetic origin, i.e., a single metabolic precursor, isopentenyl diphosphate (IPP). At least 20,000 isoprenoids have been described. By definition, isoprenoids are made up of so-called isoprene (C5) units. The number of C-atoms present in the isoprenoids can be divided by five (C5, C10, C15, C20, C25, C30 and C40); although irregular isoprenoids and polyterpenes have been reported. Isoprenoid compounds are also referred to as “terpenes” or “terpenoids.” Important members of the isoprenoids include the carotenoids, sesquiterpenoids, diterpenoids, and hemiterpenes. Carotenoids include, e.g., lycopene, β-carotene, and the like, many of which function as antioxidants. Sesquiterpenoids, include, e.g., artemisinin, a compound having anti-malarial activity. Diterpenoids, include, e.g., taxol, a cancer chemotherapeutic agent.
Identification and characterization of genes involved in biosynthetic pathways is of interest in basic and applied research. Identification of genes involved in biosynthetic pathways is typically carried out by identifying mutant genes that adversely affect the pathway, and isolating the mutant gene. Such processes are time-consuming and laborious, and in many cases identify genes not directly related to the biosynthetic pathway of interest. Other standard methods used to identify new biosynthetic pathway genes involve the identification of genes with nucleotide sequence similarity to previously discovered genes. However, these methods have limitations, as undiscovered biosynthetic pathway gene products may not bear sequence similarity to known biosynthetic pathway gene products. As such, there is a need in the art for methods of identifying genes involved in biosynthetic pathways. The present invention addresses this need.